In a message dated 1/21/2005 10:03:07 AM Central Standard Time, kenpowell@comcast.net writes:

<< Ernest, absolutely the best explanation I have ever heard.  I was trying to explain this to a friend recently and just couldn't seem to present it in a manner that he could visualize.  I'll try again using your explanation.

Ken Powell Bryant, Arkansas  >>


I cannot picture cracking motor fuel into a number of compounds in the milisecond or two it spends in the runner. While there may be a number of differing velocities measurable in the runners, they will not be far enough apart to affect the product be burned. When the mixture is exposed to the 375-400 degree rotor face, and then compressed about 9 times its volume, I suggest that it is more likely to recombine any faulty mixture.

I can picture wetting the outside of a turn in that runner at low velocities, and perhaps if a very large number of other situations exist inside that engine, you could get it to detonate. But detonation would have to be the goal of the experiment, and getting it to work would be difficult. The NA rotary does not detonate under anything like ordinary use. So if the engine was highly loaded at low revs, and the gross mixture was reduced from near ideal to just leaner, with a very low octane fuel, it might be possible to get it to detonate. Detonation is charge temperature dependant. Nothing else. A long list of factors are involved in producing the high charge temperature.

Ignition timing, octane, RPM, plug heat range, carbon deposits and oil fouling are just a few. Fuel dropping out of suspension suggests a change in velocity in a fixed system.
However moving from a homgenious mixture to something less just takes the removal of some energy from the flow, such as reducing the throttle setting just slightly, or inlet air temp dropping slightly. The precip of fuel droplets makes the mixture look leaner to the engine (any engine). Remember pulling the choke out on cold days? The mixture that runs fine on a warm day (rich enough) will not even allow a start on a cold day, because that mixture precips into large droplets and (due to reduced surface area) becomes too lean to even light.

A NA rotary can be loaded on the dyno and taken from too rich to run, through too lean to run, with no damage at all. Lynn E. Hanover